Regardless of previous gym and exercise experience, many clients and potential clients are seeking weight loss,and particularly a reduction in body fat levels. Traditionally weight loss and body fat reduction has been linked with low intensity cardio training, in the ‘fat burning’ zone (55-65% MHR). But is this correct, and is this effective? Recent studies have shown that whilst fat is the energy used during low intensity training, it is the increased metabolic rate during the recovery period from higher intensity training which is responsible for greater reduction in body fat levels.
In 1994, Tremblay et al produced the results of their study “Impact of exercise intensity on body fatness and skeletal muscle metabolism”. The study compared two groups of young adults on different training plans – a 20 week endurance training (ET) program (low intensity cardio) and a 15 week High Intensity Intermittent Training (HIIT) program (unconventional training methods are a great way of training HIIT). The mean estimated total energy cost of the ET program was 120.4 MJ (28757kcal), where as the corresponding value for the HIIT program was 57.9 MJ (14259kcal). Despite its lower energy cost, the HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with the ET program. When corrected for the energy cost of training, the decrease in the sum of sixsubcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program. (Tremblay, A., J. Simoneau, and C. Bouchard, Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism.Metabolism.43:814-818, 1994. http://www.ncbi.nlm.nih.gov/pubmed/8028502)
So in simple terms, calorie for calorie burned, HIIT trainers had a 9 times greater loss in bodyfat levels!
Further studies, including “Bodyfat Deposition: Effects of Dietary Fat and Two Exercise Protocols” by Pacheco-Sanchez, M., and K.K. Grunewald (1994), “The Effects of Exercise Intensity on Body Composition, Weight Loss, and Dietary Composition in Women”by Bryner, R.W., R.C. Toffle, I.H. Ullrish, and R.A. Yeater (1997 have reached similar conclusions.
In 1999 Kraemer et al went on to show weight training within an exercise program will yield better results than just diet, or diet and aerobic exercise. All 3 groups lost weight, however whilst the group partaking in all 3 aspects lost the same overall weight as the other two groups, they lost twice as much body fat, thereby maintaining lean muscle mass for a body which is more effective, efficient, and better looking. “Influence of Exercise Training on Physiological and Performance Changes with Weight Loss in Men” Kraemer, W.J.,et al (1999) http://www.ncbi.nlm.nih.gov/pubmed/10487375
There are many other studies supporting these findings. When it comes to body fat reduction, evidence has shown that High Intensity interval (anaerobic, 80-90% MHR) training is the most effective for increasing the body's post workout metabolism. Next effective is Low Intensity interval training (Aerobic 70- 80% MHR), and finally least effective is low intensity steady state cardio (55-65% MHR). However it should be noted that in order for any training to be effective, diet and lifestyle must also be correct.
